1. Field of the Invention
The present invention is concerned with providing new multi-layered paper and tissue products which contain foam deposited paper layers having different tensile strength ratios, and with providing products which contain both foam deposited and water deposited paper layers having different tensile strength ratios. The invention is also concerned with providing a novel process for the manufacture of such multi-layered paper and tissue products.
2. Discussion of Related Art
U.S. Pat. No. 3,716,449 of Gatward et al discloses a method and apparatus for preparing non-woven fibrous webs, including paper from a foamed aqueous furnish containing a surfactant. The disclosed method permits depositing foamed fibrous suspensions upon a previously formed mat. However, there is no disclosure of the formation of multi-layered paper or tissue containing multi-layered papers having foamed deposited layers possessing differing tensile strength ratios, and/or papers containing both foam and conventional aqueous deposited layers having differing tensile strength ratios. Likewise, there is no disclosure of functional advantages associated with such a product. U.S. Pat. No. 3,716,449 is expressly incorporated by reference herein.
U.S. Pat. No. 4,344,818 of Nuttall et al discloses a method of forming a multi-layered absorbent web containing in an inner layer thereof airborne fibers. The disclosed method utilizes a single headbox to deposit the different layers of the multi-layer absorbent web. The primary goal of Nuttall et al is to provide a multi-layer web having a significant portion of its fibers in a dry state so that less energy is required to dry the produced product. There is no disclosure of the formation of multi-layered products such as provided for herein, or of functional advantages associated with such products.
U.S. Pat. No. 4,349,414 of Stenberg discloses a method of producing a stratified jet of paper making stock, capable of creating a multi-layer web. The stratified jet initially contains separate jets of paper making stock, separated by wedge-shaped bodies of gaseous fluids. The purpose of providing such a stratified jet of paper stocks is disclosed as allowing one to produce a multi-layer web comprising a plurality of distinct layers intermingled only at adjoining layer surfaces. In one specific embodiment, Stenberg teaches that an appropriate foam stock layer can allow one to create a suitable wedge-shaped body of gaseous fluid, such as referred to above, so that layers of non-foamed stock can be prevented from mixing. Even so, the reference never produces multi-layered products such as occur in the present invention or recognizes the functional advantages associated with such products.
U.S. Pat. No. 3,594,544 of Curry et al discloses a method and apparatus for making a multi-ply paper sheet, wherein a first web is formed by wet laying fibers and a second layer is formed by dry-laying fibers, the two webs being combined to form a multi-ply sheet. There is not disclosed the use of a foam deposited layer(s), such as occurs in the present invention.